The genuine frigate--that is to say, a large cruiser, of relatively high speed, carrying its main armament on one deck--was introduced into the Royal Navy in 1741, when the _Adventure_ was built. She carried thirty-two guns, of which twenty-two were 12-pounders. The first British 36-gun frigates were the _Brilliant_ and _Pallas_, built in 1757. Their main armament also consisted of 12-pounders. French frigates of the same date were of larger dimensions, as is proved by the following table which compares the principal measurements of the _Brilliant_ and of the French frigate _Aurore_:-- ----------+-----------+-----------+---------------------------------- Name of | Length of | Breadth. | Depth of | Tonnage. | Complement. ship. | gun-deck. | | hold. | | ----------+-----------+-----------+----------+----------+------------ | ft. in. | ft. in. | ft. in. | | | | | | | Brilliant | 128 4 | 35 8 | 12 4 | 718 | 240 Aurore | 144 0 | 38 8-1/2 | 15 2 | 946 | 250 | | | | | ----------+-----------+-----------+----------+----------+------------ In the year 1761 a most important improvement was introduced, which greatly increased the usefulness of ships. This was the discovery of the value of copper plates as a material for sheathing their bottoms. Previously to this period lead was the metal used for sheathing purposes, and even it was only employed occasionally. In other cases the bottoms of vessels were paid over with various compositions, the majority of which fouled rapidly. The first vessel in the navy that was copper-sheathed was the _Alarm_, a 32-gun frigate. At first the use of copper caused serious oxidation of the iron bolts employed in the bottom fastenings, and copper bolts were substituted for them. About the year 1788 the dimensions of the various rates were again increased in order to keep pace with the improved French and Spanish ships. In the year 1780 the 38-gun frigate founded on a French model was introduced into the navy, and continued to be much used throughout the great wars at the close of the eighteenth and the commencement of the nineteenth century. The first British frigate of this rating was the _Minerva_, which measured 141 ft. in length of gun-deck; 38 ft. 10 in. width of beam; 13 ft. 9 in. depth of hold, and 940 tons--figures which were evidently based on those of the _Aurore_, captured in 1758 (see p. 128). In 1781 and 1782 two very large French frigates were captured. Their names were the _Artois_ and _Aigle_, and they exceeded in size anything in this class that had yet been built. The length of gun-deck measured 158 ft.; width, 40 ft. 4 in.; depth of hold, 13 ft. 6 in.; tonnage, 1,152; they each carried 42 guns and 280 men.